The present invention refers in general to the manufacture of carbon fiber pieces or structures, preferably in the aeronautical industry.
More in particular, the invention refers to method for managing a plurality of equipment pieces and operations within a factory for the manufacture of carbon fiber pieces, in order to increase production rate and reduce thereby manufacturing costs. The method of the invention also allows detection and correction of causes of defects or low quality, hence the method of the invention also improves quality of the final product.
The invention provides a methodology for detecting and correcting causes which reduce production efficiency, in industries with low productivity cadence.
Traditional methodologies for improving the efficiency of a factory have been implemented mainly in the automotive industry, wherein Total Productive Maintenance (TPM) methods are used for improved machine availability through better utilization of maintenance and production resources.
The Overall Equipment Effectiveness (OEE) it is a well-known methodology for measuring efficiency of each facility or equipment in a factory. With the OEE a percentage value is calculated which indicates to what extent the actual effectiveness in each case reaches a planned production rate according to standards. OEE split the performance of a manufacturing unit into three separate but measurable concepts: availability, productivity, and quality. Therefore, the OEE is calculated as:OEE=availability×productivity×quality.
Each concept of the equation points to an aspect of the process that can be improved.
The OEE is characterized by the following aspects:                Good pieces are considered rather than defective pieces.        Real manufactured pieces are considered rather than planned pieces.        Various pieces are necessary for an OEE to be calculated.        The OEE is mostly suitable for processes wherein quality control is based on a selection “pass-not pass”, wherein it is economically acceptable to convert defective products into scrap, since the value of the piece or added value of the process is not too high.        The OEE comprises “x” pieces manufactured in one period of time, e.g.: an OEE of 85% for 2000 pieces manufactured in 2 days.        Time which has not been productive is subtracted from the time scheduled according to standards for the pieces (100% OEE).        The OEE starts at 100%, this percentage representing the total time scheduled to produce various pieces. Once the scheduled time has elapsed it is determined whether or not all the pieces hoped for have been manufactured. When there are fewer units, the difference is assigned to each one of the six OEE loss categories. The OEE percentage is calculated by dividing the good pieces produced by the number of planned pieces.        
The US patent applications US2008/0010109A1, US2002/0099463A1 are examples of systems for managing a plurality of equipment pieces based on the calculation of the OEE.
The OEE (Overall Equipment Effectiveness) is, by definition, the measurement of the overall efficiency of a machine, thus, it is only possible to measure efficiency of that machine after a large number of units have been produced. However, the OEE is not capable of measuring efficiency during each operation or sub-process needed for the manufacture of a single piece or unit. Specifically, the OEE is not a suitable methodology to measure efficiency in those operations where the quality of a piece cannot be measured as soon as it has been produced, but after several days or even weeks, as is the case of the production of carbon fiber components for the aeronautical industry.
Consequently, the OEE is a suitable method for measuring efficiency in traditional industries such as metallurgy in general, automotive industry, electronic components, etc., wherein large series of pieces are produced per day with standard quality, and wherein the quality control is based on the concept good pieces—pass/defective pieces—do not pass.
However, during the conception of the present invention, it has been realized that for other types of industries with different production dynamic with low cadence of produced pieces, wherein the manufacturing process is highly sophisticated and complex, the OEE is not a good methodology to improve efficiency, because the OEE is not capable of measuring adequately all aspects influencing final product quality, process efficiency and optimal equipment performance.
In the case of factories with low production cadence, such as a factory for the production of carbon fiber components for the aeronautic industry, it might take even several days to produce for example a single panel made of carbon fiber.
The operation of equipment pieces and processes used for processing carbon fiber, such a Tape Laying Technology (ATL) equipment, a fiber placement equipment, etc., is highly complex and is affected by many operating parameters influencing directly in the quality of the final product.
The application of the OEE to such equipment pieces and processes, only serve to correct minor factors and to take few superficial correcting actions, with no practical effect in improving efficiency of the process. Many relevant operating parameters would not be considered by the OEE, thus, significant problems or causes of low effectiveness remain hidden to the method and are not corrected.